Leprosy (also known Hansen's disease) is an infectious disease caused by Mycobacterium leprae that involves the skin and peripheral nerves. Leprosy is an important global health concern; early diagnosis and a full course of treatment are critical for preventing lifelong neuropathy and disability [1].

Leprosy remains poorly understood and often feared by the general public and even by some in the healthcare professions, although (contrary to popular folklore) it is not highly contagious, and very effective treatment is available [2,3]. Although the infection is highly responsive to treatment, disabilities of the eyes, hands, and feet due to neuropathy are often not reversible and may require lifelong care and rehabilitation. Therefore, early diagnosis and management are necessary to minimize the likelihood of these disabilities [4].

The epidemiology, microbiology, clinical manifestations, and diagnosis of leprosy are reviewed here. Issues related to treatment are discussed separately. (See "Treatment and prevention of leprosy".)

EPIDEMIOLOGY

In the 1990s, the World Health Organization (WHO) established a goal of eliminating leprosy as a public health problem by the year 2000; "elimination" was defined as a reduction in prevalence to <1 case per 10,000 population in all endemic countries. Between 1985 and 2011, the number of registered cases fell from 5.4 million to 219,075; the prevalence rate per 10,000 fell from 21.1 to 0.37; these figures exclude Europe [5].

The prevalence of leprosy is variable; the overwhelming majority of cases are found in developing countries. Of the 16 countries reporting more than 1000 new cases annually in 2009, the greatest numbers of new cases were seen in India, Brazil, Indonesia, Bangladesh, and Nigeria [1]. With increasing international travel, however, patients with leprosy may present anywhere.

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